Centrifugal pump



Nov. 23,1948.

0. JACOBSEN CENTRIFUGAL rum 2 Sheets-Slieet 2 lNVENT OR I N JfioosszM .5Ovsrm Filed Aug. 23, 1944 pl 2 u A'n'oRNEYs Patented Nov. 23, 1948 ICEOENTRIFUGAL PUMI' Oystein Jacobsen, Montgomery County, Ohio,-

signor to The Duriron Company, Inc., Dayton, Ohio, a corporation of NewYork Application August 23, ra ned-m No. 550,749

Claims. (Cl. 103-103) a The present invention relates to centrifugalPumps and more particularly to those having a circular runner rotatablein a volute casing and in which the fluid is forced out through a singleneck in the casing.

In centrifugal pumps of the volute chamber type, it is the usualpractice to draw liquid or gas through a central inlet port leading tothe hub portion of the impeller and to discharge the fluid bycentrifugal force from the impeller through a tangentialport or neck inthe wall of the casing. This port is generally of circular-shape and isgiven a somewhat curvilinear shape to extend gently away from theperiphery of the impeller in order to reduce as far as possible eddycurrents or turbulence within the fluid which is being forced out of thepump.

Nothwithstanding the extreme caretaken in the design of, the casingoutlet to give it the maximum stream-line effect, it has been foundpath. These guide-ways are contained in the r with the high pressureside of the impeller.

that there is still a sumcient amount of whirling present which disturbsthe orderly flow of fluid through the restricted neck opening and theseeddy currents materially reduce the efficiency of the pump. Afterconsiderable investigation of this old but hitherto unsolved problem, Ihave found that the turbulence effect, in the case of a circular columnof fluid, originates at the central part of the column. This may be dueto the retarding effects offered by the walls of the outlet passagewayto the fluid but which do not affect the central portion of the fluidcolumn thustending to permit the various parts of the column to travelat different velocities. Moreover, the interior surfaces of the outletconduit or neck of the pump serve effectively to guide that portion ofthe fluid near. these surfaces but the interior portions of the fluidcolumn must provide their own guiding" effects since they areconsiderably removed from the guiding surfaces.

The primary object of the invention is to provide an improvedcentrifugal pump having an outlet passageway arranged tangential to theimpeller and in which turbulence and other retarding circulatory effectswithin the fluid moving between the impeller and the external surface ofthe casing are entirely removed. Thus the general object of theinvention is to improve the efficiency of pumps which employ impellersrotating within a volute casing.

These objects are attained in brief, by separating the outgoing columnof fluid into'two or more portions and providing separate guide-ways foreach fluid column in order to constrain every portion of the outgoingfluid to a predetermined usual pressure outlet of the casing to formindividual passageways which communicate solely Thus the fluid flowsthrough all of the passageways formed by the guides under substantiallyequal pressures and at relatively the same veloc-" ities. For practicalpurposes, the guides for controlling the interior portions of the fluidcolumn may be formed integral as by casting with the usual neck of thecasing.

The invention will be better understood when reference is made to thefollowing description and the accompanying drawings in which Figure 1represents a longitudinal section of the improved pump with a few partsshown in elevation for clearness.

Figure 2 is a cross-sectional view of the pump taken along line 2-4 inFigure l and looking in the direction of the arrows.

I Figure 3 is a cross-sectional view taken across the neck of the casingas represented by the line 3-3 in Figure 2.

Referring to the drawings, reference character I designates the maincasting of the centrifugal pump, this casing taking on generally avolute shape as indicated in Figure 2. The right-hand side of the casingas seen in Figure 1 is provided with a large circular opening 2 andterminates in a bearing surface 3. A cover plate l has a flanged portion5 which bears against the surface 3 and is provided with a shoulder 6which fits loosely within the opening 2 of the casing. A large. packingwasher may be inserted between the bearing surface 3 and the flangeportion 5 in order to prevent leakage at this point.

The interior surface I of the cover 4 together with interior surface 8of the casing I provides a pumping chamber or compartment in which theimpeller of the pump generally designated 9 rotates. The cover member 4is provided with a long, outwardly extending cylinder I'll positioned atthe center of the cover and provided with an internal passageway lltapered to a smaller ditending longitudinally thereof in order tofurther minimize eddy current loss.

The casing is provided opposite the cylinder ill with an outwardlyextending cylinder l4 preferably formed integral with the casing. Thecylinder is hollow as indicated at I5 to receive a large number ofpacking rings l6 for preventing leakage of fluid at this point. Thedepth of the opening I5 is less than the length of the cylinder It inorder to leave a wall portion l1 having an opening Hi. This openingsnugly but slidably receives a shaft is on which is mounted the impeller9. The packing rings it which are contained within the annular spacebetween the shaft is and the opening l5 are placed under pressure by agland 20 which has 9, turned down portion 2| of slightly less diameterthan the opening i5. Pressure may be exerted on the gland by means of aclamping device (not shown) embracing the flange 22 of the gland and anenlargement 23 on the cylinder it.

The main portion of the casing is supported in a heavy frame member 2%which flts within a shouldered portion 25 of the casing. The latter andthe cover d are secured together by means of a clamping ring 26 andbolts 2i which threadedly engage the frame 2d.

The impeller may be of the double shrouded type as illustrated, or anopen runner and, in general, comprises a heavy circular plate 28 whichis provided at the center with a hub 29 having an opening 3|) forreceiving the turned down portion 3| of the shaft it. Theshaft portion3| is threaded at the end indicated 32 for engaging a nut 33 which fitswithin a countersunk opening 3 3 formed in the hub. The innermost end ofthe shaft portion Si is preferably tapered to a point indicated at 35 inorder readily to direct the fluid which flows through the inlet openinginto the passageways formed by the blades of the impeller.

As shown in Figure 2, these blades may constitute a number ofcurvilinear sheet-like projections 36 extending integrally upward fromthe plate 28 with which they may be cast. The blades have a roundedshape of varying degrees of ourvature and in general are much more fiatat their outer edges than near the center. They extend from a positionconforming to a circle at the center of the plate 28 to an outerposition which coincides with the edge of the plate. There is a secondplate or shroud 31 preferably secured to the edges of the blades 36 andboth plates 28, 31 together with the blades 36 constitute the im peller.The shrouds 28 and 31 at their inner edges are provided with curvedsurfaces 38 and the outer plate or shroud 31 has an opening 39 whichcoincides with the inlet passageway The interior surface of the casingtakes the shape of a volute, as shown in Figure 2, and there isconsiderable space between the outer edge of the shrouds 28, 31 and theinterior surface of the casing. In order to divide the suction andpressure'eifects of the impeller, the casing is provided with arelatively sharp inwardly projecting portion 40 which terminates quiteclose to the periphery of the impeller. The output of the pump is takenthrough a single neck 4| which extends upwardly and has curvilinearshape so that the interior surface of the neck can gradually merge withthe interior space of the pump in a tangential direction. At theopposite or lower side of the casing a drainage hole "is taken outthrough a boss 43 having lugs 44. A closure plate {5 is bolted asindicated l is discharged through the opening in the neck 5|, usuallyinto a large pipe or conduit (not shown) clamped to the enlarged portion48. In order to constrain all of the fluid which flnds its way into theannular space between the impeller and the volute casing to pass throughthe vane passageways, the outer shroud 31 is curved outwardly asindicated at t5 and terminates at a position quite close to the flatsurface of the cover extension l2. The projection 40 of the casing tendsto reduce the amount of fluid which continuously circulates within thepump so that the maximum amount of fluid is caused to enter the outletpassageway.

Notwithstanding the taken to eliminate all sharp corners and to providethe passageways with gentle curves designed to offer the minimum amountof resistance to flow, it has been found that severe turbulence or eddycurrent loss still exists in the lower or throat portion of the neck 4|.While I do not desire'to be limited to any theory, it is believed thatthis eddy current loss or interference with free flow is due in part tothe skin effect of the interior surfaces of the neck which affects theouter portions of the stream greater than those on the interior.

In accordance with my invention there is provided within the usual neck4| of the casing a guide vane 56 which, in general, conforms to theshape of the opening within the neck as can be seen in Figure 2 and alsoterminates in a position indicated at 50 which is quite close to theoutside periphery of the impeller; This guide vane preferably extendsthroughout the entire length of the neck 4| to form two passageways forthe fluid which is being discharged by the pump. As shown in Figure 3,the guiding vane 60 can be given a curvilinear shape as seen incross-section and, therefore, can be made integral as the casting withinthe casing neck. It will be noted in Figure 2 that each of theprojections 40 and 50 extend in relatively the same direction and pointtangentially with respect to the impeller in the pressure zone created.by the impeller. Thus, as the impeller is rotated, the fluid which maybe water, an acid containing solution or gas, is caused to flow in partthrough the first passageway encountered, namely 5|, in the neck 4| andthe remaining portion of the fluid is caused to flow through thepassageway 52 which is also positioned in the same neck portion. Byproperly stream-lining the guide vane 50 and carefully determining itslateral position within the neck 4 I, all loss in head by turbulence oreddying which normally takes place at the position where the annularspace about the impeller merges with the opening in the neck iseliminated. The effectiveness of the guide vane 50 in facilitating theflow through the neck 4| is so pronounced that the output of the pump isgreatly increased, notwithstanding the inevitable obstruction introducedin the neck by the end portion of the guide vane.

. X It will be noted'that the use of this vane in-- extreme precautionstroduces no complication of design because the neck 4| is of standardshape and size and the only difference of structure necessitated by myinvention is that the guide vane 50 is cast within the neck or securedthereto in any other suitable manner. Due to the fact that the entrancesto the passageways 5i and 52 are positioned near the periphery of theimpeller, close together, and

are separated only by the thickness of the partition 50 both passageways5| and 52 deliver pressure fluid in an outward direction as indicated,

by the arrows. The entire interior of the neck 4| with the exception ofthe partition is available for carrying fluid pumped by the impellerinto the discharge pipe.

It will be understood that I desire to comprehend within my inventionsuch modifications as come within the scope of the claims and theinvention.

Having thus fully set forth and described my invention, what I claim asnew and desire to secure by United States Letters Patent, is:

1. In a pump, a casing of volute shape and having a single inlet and asingle outlet passageway, an impeller mounted in the casing'to forcefluid from the inlet to theoutlet passageway, a plurality of vanesmounted on said impeller, and means for preventing turbulence betweenthe outlet passageway and the area immediately surrounding the impellerat the position where the passageway merges with the inter-vane space atthe periphery of the impeller, said means including a guide vaneextending through the outlet passageway and beginning at a position nearthe periphery oi the impeller closest to the outlet passageway, and aprojection extending inwardly from the casing as far as the impeller toseparate the suction and.

pressure effects of the impeller.

2. A pump comprising acasing of volute shape and having a volutechamber, a circular impeller provided with curvilinear blades mountedwithin the casing to leave a space of varying width between theperiphery of the impeller and the interior of the casing, a single inletpassageway entering the casing at about the center thereof, an outletpassageway merging tangentially with the space between the impeller andthe casing,

'and a single guide vane extending the entire length of theoutletpassageway and terminating at a position adjacent the periphery ofthe impeller and nearest to the outlet passageway, and aprojectlonextending inwardly fromthe casing as far as the impeller toseparate the suction and pressure effects of the impeller;

3. A pump comprising a casing of volute shape and having a single inletpassageway at its cen ter, said casing being provided with an outwardlyextending hollow neck which forms the outlet passageway, an impeller inthe casing including a plurality oi vanes, the inner portions of theinter-vane compartments communicating with the inlet passageway, theouter portions of the inter-vane compartments communicating with2,291,478 the interior of the casing neck, and a single gufdeifi.

vane in said neck termlnating'at a position where the outlet passagewaymerges with the nearest outer portions of the inter-vane passageways,and a projection extending inwardly from the casing as far as theimpeller to separate the suction and pressure effects of the impeller.

4. A pump comprising a casing of volute shape and having a single inletpassageway at its center, said casing being provided with an outwardlyextending hollow neck whiclrforms the outlet passageway, an impeller inthe casing including a pluralityof vanes, the inner portions of theinter-vane compartments communicating with the inlet passageway, theouter portions of the inter-vane compartments communicating with theinterior of the casing neck, and a guide vane in said neck terminatingat a position where the outlet passageway merges with the nearest outerportions of the inter-vane passageways, said guide vane having acurvilinear shape in cross-section and being integrally secure to'theinterior of said neck, and a projection extending inwardly from thecasing, substantially parallel to said guide vane as far as the impellerto separate the suction and pressure eflects of the impeller.

5. A pump comprising a casing of volute shape and having a single inletpassageway at its center, said casing being provided with an outwardlyextending hollow neck which forms the outlet passageway, an impeller inthe casing including a plurality of vanes, and a partition extendingacross the interior of said neck only as far as a point on the peripheryof said impeller and a projection extending inwardly from the casing,

substantially parallel to said partition as far as the impeller toseparate the suction and pressure eflects of the impeller.

6. A pump comprising a casing of volute shape REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number 7 Name Date 111,026 Williams Jan. 17, 1871929,230 Landrum et al. July 27,1909 1,065,'731 Scheneible June 24, 19131,258,545 Dudley Mar. -5, 1918 1,390,391 Skidmore, Jr Sept, 13, 19212,019,143 LaBour Oct. 29, 1935 LaBour July 28, 1942

